Flow rate ratio variable type fluid supply apparatus

ABSTRACT

A flow rate ratio variable type fluid supply apparatus includes a flow rate control system supplying gas of flow rate Q that is diverted to first flow diverting pipe passage and second flow diverting pipe passage with prescribed flow rates Q 1 /Q 0  so gas is supplied to a chamber, and a first orifice having opening area S 1  is installed on the first flow diverting passage, and the second flow diverting passage is connected to a plurality of branch pipe passages connected in parallel, orifices having opening area installed on the branch passages, and open/close valves installed on all, or some of, the branch passages so gas is diverted to flow diverting passages with flow rate ratio Q 1 /Q 0  equivalent to the ratio of the first orifice and the total opening area S 2 o of flow passable orifices of the second flow diverting passage by regulating total opening area of the flow passable orifices.

This is a National Phase Application in the United States ofInternational Patent Application No. PCT/JP2007/000629 filed Jun. 13,2007, which claims priority on Japanese Patent Application No.2006-177156, filed Jun. 27, 2006. The entire disclosures of the abovepatent applications are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention is used for semiconductor manufacturingfacilities, and the like, and relates to a flow rate ratio variable typefluid supply apparatus that makes it possible to divert a gas of a setflow rate supplied from a flow rate control system so that it issupplied to a chamber with a desired flow rate ratio.

BACKGROUND OF THE INVENTION

In recent years, there has been a trend seen in that silicon wafershaving a larger diameter are used for semiconductor manufacturing. Forthis reason, when semiconductor manufacturing apparatuses are used, ithas become necessary to supply a treatment gas to a chamber through aplurality of supply lines, and to precisely control a flow rate ratio ofthe gas passing through these supply lines.

FIG. 7 illustrates one example of a gas supply system with which gas issupplied to a chamber through a plurality of supply lines for aconventional semiconductor manufacturing apparatus, wherein flow ratecontrol systems FCS₁, FCS₂ are provided with gas supply lines GL₁, GL₂,respectively, thus allowing regulation of the flow rate ratio γ=Q₁/Q₂ ofthe supply lines GL₁, GL₂. In FIG. 7, S_(T) designates a gas supplyline, G designates a treatment gas, C designates a chamber, D designatesa gas discharger, H designates a wafer, and I designates a wafer holdingbase. However, with the apparatus as shown in FIG. 7, two flow ratecontrol system units FCS₁, FCS₂ are required, which upsizes thesemiconductor manufacturing apparatus and raises costs for equipment andmaintenance, thus making it difficult to downsize equipment and toreduce costs.

FIG. 8 shows gas supply equipment previously developed by the inventorof the present invention in order to improve the aforementionedshortcomings of the equipment shown in FIG. 7, wherein gas G iscontrolled to have a flow rate Q set by the flow rate control system FCSso that gas G is supplied to a chamber C with a desired flow rate ratioγ=Q₁/Q₂ through supply lines GL₁, GL₂, which are provided with pressuretype diverted flow rate controllers FV₁, FV₂ controlled by a divertedflow rate control apparatus FRC.

In particular, the gas supply apparatus shown in FIG. 8 is provided witha gas discharger D, which is equipped with orifices OL₁, OL₂ havingspecific diameters φ₁, φ₂, respectively, installed inside the chamber C.The gas supply apparatus of FIG. 8 is made so that gas of a totalquantity Q=Q₁+Q₂ is supplied into the chamber C with desired divertedflow rates Q₁ and Q₂, expressed by Q₁=K₁P₃′ and Q₂=K₂P₃″ (where K₁ andK₂ are constants determined by the cross sectional areas, and the like,of orifices OL₁, OL₂), passing through the orifices OL₁, OL₂,respectively, of the gas discharger D by regulating the gas pressureP₃′, P₃″ on the downstream side by using the diverted flow ratecontrollers FV₁, FV₂. (Japanese Unexamined Patent ApplicationPublication No. 2004-5308)

However, with the gas supply apparatus shown in FIG. 8, there remains aproblem in that the shape, and the like, of the gas discharger D aresubsequently restricted because the gas supply apparatus includes thatgas discharger D, equipped with orifices OL₁, OL₂ having specifieddiameters φ₁, φ₂, installed inside the chamber C. Because two flow ratecontrol system units FCS₁, FCS₂ are not needed by the apparatus shown inFIG. 8, compared with the aforementioned gas supply apparatus shown inFIG. 7, costs for equipment, and the like, can be reduced in comparisonwith the aforementioned gas supply apparatus of FIG. 7. However, it isdisadvantageous in that the gas supply apparatus of FIG. 8 requires twodiverted flow rate controller units FV₁, FV₂, and also a diverted flowcontrol apparatus FRC. This fact doesn't allow installation costs to besubstantially reduced and it doesn't allow drastic downsizing of thediverted gas supply apparatus. In addition, another disadvantage is thatit becomes too complicated to control of the flow rate ratio Q₁/Q₂.

Furthermore, FIG. 9 illustrates another system that has been developedpreviously by the inventors of the present invention to overcome theaforementioned shortcomings of the gas supply system shown in FIG. 8(Japanese Unexamined Patent Application Publication No. 2004-5308). Thegas supply system of FIG. 9 is constituted so that by using simplystructured open/close valves V₁, V₂, a pressure type diverted flow ratecontroller SV, and a flow rate ratio control apparatus CT, the totalflow rate Q=Q₁+Q₂ of the gas flow G is supplied into the chamber C witha desired diverted flow rate ratio γ=Q₁/Q₂ in such a manner that theopen/close valve of the supply line with a larger flow rate is fullyopened and the degree of opening of a pressure type diverted flow ratecontroller SV is regulated, so as to conduct pressure adjustment of bothdiverted supply lines GL₁, GL₂ by regulating gas flow rate from a supplyline on the larger flow rate side to a supply line on the smaller flowrate side. (Japanese Unexamined Patent Application Publication No.2005-11258)

However, the same disadvantages with the aforementioned gas supplyapparatus shown in FIG. 8 (Japanese Unexamined Patent ApplicationPublication No. 2004-5308) remain unsolved even with the gas supplyapparatus of FIG. 9, so it has not been possible to substantiallydownsize the gas supply apparatus and to reduce equipment costsdrastically, and also it has not been possible to freely choose the formof the gas discharger D without limitation.

As shown in FIG. 10, flow rate control systems (Japanese UnexaminedPatent Application Publication No. 2003-323217 and others) have beendeveloped as a kind of flow diverting gas supply apparatus, whereinbranch supply passages GL₁, GL₂ are equipped with sonic velocity nozzlesSN₁, SN₂, respectively, and the pressure P₁ on the upstream side pipepassage from the sonic velocity nozzles SN₁, SN₂ is regulated using anautomatic pressure controller ACP, thus allowing gas supply quantitiesQ₁, Q₂ from the branch supply passages GL₁, GL₂ to be regulated. In FIG.10, ACQ designates a flow rate control part, and V₁, V₂ designatecontrol valves.

An object of the flow diverting supply apparatus is to simultaneouslycontrol gas flow rates Q₁, Q₂ passing through sonic velocity nozzlesSN₁, SN₂ (or orifices) in a manner such that the primary side pressureP₁ is regulated using an automatic pressure controller ACP. It is not animmediate object of the invention to regulate the flow rate ratioγ=Q₁/Q₂ of the branch pipe passages GL₁, GL₂ at any given ratio.

-   Patent Document 1: Japanese Unexamined Patent Application    Publication No. 2004-5308-   Patent Document 2: Japanese Unexamined Patent Application    Publication No. 2005-11258-   Patent Document 3: Japanese Unexamined Patent Application    Publication No. 2003-323217

OBJECT OF THE INVENTION

The primary object of the present invention is to provide a downsizedand low cost flow rate ratio variable type fluid supply apparatus thatmakes it possible to divert a gas of a prescribed flow rate Q and tosupply the diverted gas with a diverted flow rate ratio as desired byusing an extremely simply structured open/close valve and orifice. Inthis way, the present invention solves the aforementioned shortcomingsencountered with the conventional apparatus for supplying a diverted gasto a chamber, which include that substantial reduction in size and costcannot be achieved with the conventional diverted gas supply apparatusbecause the conventional apparatus requires an automatic pressurecontroller, an open/close control valve, and a control part thereof, andfurthermore, it is found that the accuracy of the conventional apparatusin controlling a diverted flow ratio is low.

SUMMARY OF THE INVENTION

Through the process of developing varied flow rate control apparatusesfor which an orifice is employed, the inventors of the present inventionhave postulated that, under the conditions of critical expansion, anextremely simply structured flow rate ratio variable type fluid supplyapparatus can produced by means of adjusting, with high accuracy, thevalue of a so-called correction coefficient of an orifice to a setvalue.

The present invention is, therefore, a creation based on theaforementioned idea of the inventors of the present invention. Thepresent invention, in accordance with a first embodiment, isfundamentally constituted so that a flow rate ratio variable type fluidsupply apparatus is used to divert a gas of a flow rate Q supplied froma flow rate control system 6 so that the gas flows to a plurality offlow diverting pipe passages 1 ₁ to 1 _(n) with prescribed flow rates Q₁to Q_(n), respectively. Thus, gas of a flow rate Q is supplied throughthe flow diverting pipe passages 1 ₁ to 1 _(n) into a chamber, andorifices 3 . . . having appropriate opening areas S₁ . . . are installedon one or a plurality of flow diverting pipe passages among theaforementioned flow diverting pipe passages 1 ₁ to 1 _(n), and theaforementioned remaining flow diverting pipe passages serve as a pipepassage to which a plurality of branch pipe passages 2 _(a) to 2 _(n)are connected in parallel, and orifices 4 . . . having appropriateopening areas S_(2O) . . . are installed on the aforementioned branchpipe passages 2 a to 2 n, respectively. Also, open/close valves V_(b) toV_(n) are installed on all, or some of, the aforementioned branch pipepassages so that gas of the flow rate Q is diverted so as to flow todiverting pipe passages 1 ₁ to 1 _(n) with a flow rate ratio of Q₁/Q₂/Q₃. . . Q_(n) equivalent to the ratio of the opening area S₁ . . . oforifices 3 on the aforementioned flow diverting pipe passages. By thisstructure, the total opening area S_(2O) of flow-passable orifices onthe flow diverting pipe passages, provided with branch pipe passages bymeans of the total opening area S_(2O) . . . of flow-passable orificesof the remaining flow diverting pipe passages, are regulated by theopen/close operation of the open/close valves Vb to Vn.

The present invention, in accordance with a second embodiment, isfundamentally constituted so that the flow rate ratio variable typefluid supply apparatus is used to divert gas of a flow rate Q so thatthe gas is supplied from the flow rate control system 6 flows to theplurality of flow diverting pipe passages 1 ₁ to 1 _(n) with prescribedflow rates Q₁ to Q₀, respectively, so that gas of flow rate Q issupplied through flow diverting pipe passages 1 ₁ to 1 _(n) into thechamber, and wherein orifices 3 ₁ to 3 _(n-1) having opening areas S₁ toS_(n-1) are installed on the aforementioned flow diverting pipe passage1 ₁ to flow diverting pipe passage 1 _(n-1), and the aforementionedremaining flow diverting pipe passage in is used as the pipe passage towhich the plurality of branch pipe passages 2 a to 2 n are connected inparallel, and orifices 4 a to 4 n having opening areas S_(2a) to S_(2n)are installed on the aforementioned branch pipe passages 2 _(a) to 2_(n), respectively. Also, open/close valves V_(b) to V_(n) are installedon all, or some of, the aforementioned branch pipe passages so that gasof flow rate Q is diverted and flows to the flow diverting pipe passages1 ₁ to 1 _(n) with a flow ratio of Q₁/Q₂/Q₃ . . . Q_(n-1)/Q₀ that isequivalent to the ratio of opening areas of orifices 3 ₁ to 3 _(n-1) onthe aforementioned flow diverting pipe passages 1 ₁ to 1 _(n) and thetotal opening area S₂₀ of the flow-passable orifice on the flowdiverting pipe passage 1 _(n) by regulating the total opening area S₂₀of flow-passable orifices on the flow diverting pipe passages 1 _(n)using the open/close operation of the open/close valves V_(b) to V_(n).

The present invention, in accordance with a third embodiment, modifiesthe first embodiment or the second embodiment so that an orifice 3 isconstituted with an orifice 3 a that has a constant opening area S₁₁ andan orifice 3 b that has an opening area S₁₂ that is adjustable and isconnected in parallel with orifice 3 a.

The present invention, in accordance with a fourth embodiment, isfundamentally constituted so that the flow rate ratio variable typefluid supply apparatus diverts gas of flow rate Q supplied from the flowrate control system 6 so that gas flows to the No. 1 flow diverting pipepassage 1 and the No. 2 flow diverting passage 2 with prescribed flowrates Q₁, Q₀, respectively, so that gas of flow rate Q is suppliedthrough both flow diverting pipe passages 1, 2 into the chamber, whereinthe No. 1 orifice 3 has an opening area S₁ and is installed on theaforementioned No. 1 flow diverting pipe passage 1, and also theaforementioned No. 2 flow diverting pipe passage 2 is made to be a pipepassage to which a plurality of branch pipe passages 2 a to 2 n areconnected in parallel, and orifices 4 a to 4 n having opening areas S₁ato S₂n are installed on the aforementioned branch pipe passages 2 a to 2n, respectively, and open/close valves Vb to Vn are installed on all, orsome of, the aforementioned branch pipe passages so that gas of flowrate Q is diverted to flow to flow diverting pipe passages 1, 2 with aflow rate ratio Q₁/Q₀ equivalent to the ratio of the opening area of theNo. 1 orifice 3 of the aforementioned No. 1 flow diverting pipe passage1 and the total opening area S₂₀ of the flow-passable orifices of theaforementioned No. 2 flow diverting pipe passage 2 by means ofregulating the total opening area S₂₀ of flow-passable orifices of theNo. 2 flow diverting pipe passage 2 by the open/close operation of theopen/close valves Vb to Vn.

The present invention, in accordance with a fifth embodiment, furthermodifies the fourth embodiment so that the No. 1 orifice 3, having anopening area S₁, is constituted with an orifice 3 a having a constantopening area S₁₁ and an orifice 3 b having an opening area S₁₂ that ismade to be adjustable and that is connected in parallel with the orifice3 a so that the No. 1 orifice 3 is formed.

The present invention, in accordance with a sixth embodiment, modifiesthe fourth embodiment so that the No. 2 flow diverting pipe passage 2 isformed by a plurality of branch pipe passages 2 a to 2 n, and theopening area S₂a of the orifice 4 a of the branch pipe passage 2 a andthe aforementioned opening area S₁ of the No. 1 orifice 3 of the No. 1flow diverting pipe passage 1 are made to be identical, and the branchpipe passage 2 a is connected to the No. 2 branch pipe passage withoutinstalling an open/close valve therebetween.

The present invention, in accordance with a seventh embodiment, furthermodifies the fourth embodiment so that the No. 2 flow diverting pipepassage 2 is formed by four branch pipe passages 2 a to 2 d, wherein theopening area S₂a of the orifice 4 a of the branch pipe passage 2 a andthe opening area S₁ of the No. 1 orifice 3 of the No. 1 branch pipepassage are made to be identical, and also the opening areas S₂b to S₄dof the orifices 4 b to 4 d of the remaining branch pipe passages 2 b to2 d are made to be 5%, 10% and 20%, respectively, of the opening area S₁of the No. 1 orifice 3 of the aforementioned No. 1 branch pipe passage,and the remaining branch pipe passages 2 b to 2 d are provided withopen/close valves Vb to Vd, respectively.

The present invention, in accordance with an eighth embodiment, furthermodifies the fourth embodiment so that the open/close valves Vd to Vnare the only ones with which branch pipe passages 2 d to 2 n can beeither fully opened or fully closed.

The present invention, in accordance with a ninth embodiment, furthermodifies the fourth embodiment so that the opening areas of orifices 3,and 4 a to 4 n can be set at appropriate values selecting the correctioncoefficient depending on the orifice shape and pressure conditions onthe upstream side from the orifices.

The present invention, in accordance with a tenth embodiment, furthermodifies the ninth embodiment so that the correction coefficient is 0.6or 0.7 depending on how the shape of a diameter φ of the orifices 3, and4 a to 4 n has been processed.

The present invention, in accordance with an eleventh embodiment,further modifies the fourth embodiment so that a gap between a diaphragmvalve body and a valve seat of a metal diaphragm is used as the No. 1orifice 3 and the No. 2 orifices 4 a to 4 n.

The present invention, in accordance with a twelfth embodiment, furthermodifies the first embodiment, the second embodiment, or the fourthembodiment, so that either the orifice 3 and the orifice 4, or the No. 1orifice 3 and the No. 2 orifices 4 a to 4 n, are made to be 2-stepcutting type orifices having 2 different orifices OL₁, OL₂, and gas ismade to flow from an orifice having a smaller diameter to an orificehaving a larger diameter.

EFFECT OF THE INVENTION

Due to the fact that a flow rate ratio variable type fluid supplyapparatus of the present invention comprises orifices having prescribeddiameters φ and extremely simple-structured open/close valves Vb to Vn,with which pipe passages can be fully opened or fully closed, it ispossible to simplify the structure of the fluid supply apparatus; thus,substantial reduction in size and cost can be achieved.

In accordance with the present invention, the flow rate ratio γ can bechanged to a plurality of steps at ease by means of switching open/closevalves Vb to Vn appropriately, and the flow diverting ratio γ can alsobe changed to a plurality of steps at ease by means of changing theorifices themselves. In addition, substantial changes of the flow rateratio γ can be easily achieved by changing the orifices themselves.

Furthermore, in accordance with the present invention, the correctioncoefficient can be strictly controlled, and the correction coefficientis made to be 0.7 for an orifice having a diameter φ of 0.3 mm or more,and 0.6 for an orifice having a diameter φ of 0.3 mm or less, dependingon the shape of processing. Hence, the flow rate ratio variable typefluid supply apparatus, in accordance with the present invention, canreduce the error of the flow diverting ratio Q₁, Q₂ to less than 1% S.P.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an embodiment of a flow rate ratio variabletype fluid supply apparatus in accordance with the present invention.

FIG. 2 is a cross sectional view of a 1-step cutting type orifice.

FIG. 3 is across sectional view of a 2-step cutting type orifice.

FIG. 4 is a block diagram of a test device for testing flow ratecharacteristics of an orifice.

FIGS. 5 a and 5 b show flow rate characteristics of orifices of diameterφ=0.1 mm and φ=0.55 mm, respectively, and computation values of thecorresponding correction coefficient of these orifices.

FIG. 6 shows the relationship between pressure P₁ on the upstream sidefrom an orifice and the flow rate measuring error (rdg error) in thecase when pressure P₂ on the downstream side from an orifice OF is madeto be 20 Torr.

FIG. 7 is an explanatory drawing of a conventional gas supply apparatusfor a chamber that employs a plurality of lines.

FIG. 8 is another explanatory drawing of another conventional gas supplyapparatus for a chamber that employs a plurality of lines.

FIG. 9 is yet another explanatory drawing of yet another conventionalgas supply apparatus for a chamber that employs a plurality of lines.

FIG. 10 is an explanatory drawing showing one example of a conventionalflow diverting gas supply apparatus that employs a sonic velocitynozzle.

FIG. 11 is a block diagram of another embodiment of a flow rate ratiovariable type fluid supply apparatus in accordance with the presentinvention.

FIG. 12 is a block diagram of another embodiment of a flow rate ratiovariable type fluid supply apparatus in accordance with the presentinvention.

REFERENCE CHARACTERS AND NUMERALS

-   -   A Flow rate ratio variable type fluid supply apparatus    -   G Gas    -   Q Total flow rate    -   Q₁ to Q_(n) Flow rate of the No. 1 flow diverting pipe passages    -   Q₀ Flow rate of the No. 2 flow diverting pipe passage    -   Q_(a) to Q_(d) Flow rates of diverting or branch pipe passages    -   γ Flow rate ratio (Q₁/Q₀)    -   OF Orifice member    -   OL, OL₁, OL₂ Orifices    -   1 No. 1 flow diverting pipe passages    -   2 No. 2 flow diverting pipe passage    -   2 a to 2 d Branch pipe passages    -   3 No. 1 orifices    -   4 No. 2 orifices    -   S_(T) Cross sectional area of the total orifice openings    -   S₁ to S_(n) Opening area of No. 1 orifices    -   S₂a to S₂d Opening area of Branch pipe passage orifices    -   S₂o Total opening area of flow-passable orifices of the No. 2        flow diverting pipe passage 2    -   φ Orifice diameter    -   Vb to Vd Open/Close valves    -   5 Gas supply source    -   6 Flow rate control system    -   7 Process chamber    -   8 a, 8 b N₂ supply sources    -   9 Mol block    -   10 a, 10 b Pressure regulators    -   11 Vacuum gauge    -   12 Open/close control valve    -   13 Vacuum pump    -   P₂ Internal gas pressure of the pipe passage    -   P₃ Internal pressure of the chamber    -   A_(1a) A source of air    -   PS₁ Pressure detector of the pipe passage GL₁    -   PS₂ Pressure detector of the pipe passage GL₂    -   14 Outlets

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments in accordance with the present invention areexplained hereinafter with reference to drawings. FIG. 1 is a blockdiagram of a flow rate ratio variable type fluid supply apparatus inaccordance with the present invention. In FIG. 1, A designates the flowrate ratio variable type fluid supply apparatus, Q, Q_(a) to Q_(d) andQo designate flow rates, 1 designates the No. 1 flow diverting pipepassage, 2 designates the No. 2 flow diverting pipe passage, 2 a, 2 b, 2c, 2 d designate branch pipe passages, 3 designates that No. 1 orifice,4 a designates the No. 2 orifice, 4 b designates the No. 3 orifice, 4 cdesignates the No. 4 orifice, 4 d designates the No. 5 orifice, S₁, andS₂a to S₂d designate cross sectional areas of orifices, Vb, Vc, Vddesignate open/close valves, 5 designates a gas supply source, 6designates a flow rate control system and 7 designates a processchamber.

The aforementioned fluid supply source 5 is a supply source of variouskinds of gas to be used for semiconductor manufacturing. In accordancewith the present embodiment, a N₂ gas supply source is provided. Theflow rate control system 6 regulates the gas flow rate Q supplied to theprocess chamber 7 at a given flow rate. In accordance with the presentembodiment, the apparatus A is made so that N₂ gas of a flow rate Q=1SLM is supplied with the aid of a pressure type flow rate control systemFCS.

In accordance with the present embodiment, a chamber having an internalpressure that is regulated to be 10 Torr is employed as theaforementioned process chamber 7, and N₂ gas of a desired flow rate Q₁is supplied through the No. 1 flow diverting pipe passage 1 to thecenter part thereof, and N₂ gas of a flow rate Q₂ is supplied throughthe No. 2 flow diverting pipe passage 2 to the peripheral part thereof,respectively.

Gas G supplied from the aforementioned gas supply source 5 is regulatedto have a flow rate of, for example, Q=1 SLM using the flow rate controlsystem 6, and then the gas is supplied into the process chamber 7through the No. 1 flow diverting pipe passage 1 and the No. 2 flowdiverting pipe passage 2. The flow rate ratio γ=Q₁/Q₀ of gas flowpassing through the flow diverting pipe passages 1, 2 is regulatedaccording to the predetermined flow diverting ratio γ=Q₁/Q₀ by means ofopen/close valves Vb to Vd that are made to be appropriately switchedfor opening/closing (i.e., full opening or full closing). In accordancewith the present embodiment, as mentioned before, N₂ gas of Q=1 SLM issupplied as a quantified amount from the flow rate control system 6. Inaccordance with the present specification, the terms “flow rate ratio”and “flow diverting ratio” are synonymous terms.

With the present embodiment, as below stated, the aforementioned flowrate ratio γ=Q₁/Q₀ is made so that it can be regulated from 1/1 to1/1.35 in steps of 5%, thus totaling 8 steps (that is, 1/1, 1/1.05,1/1.1, 1/1.15, 1/1.20, 1/1.25, 1/1.30, 1/1.35) by means of switching theopen/close valves Vc to Vd.

Referring to FIG. 1, the gas flow rate passing through orifices 3, and 4a to 4 d is in proportion to the cross sectional area of orifices 3, and4 a to 4 d when so-called “expansion conditions” are maintained betweenpressure P₁ on the upstream side and pressure P₂₁ and P₂₂ on thedownstream side from orifices 3, and 4 a to 4 d. Specifically, undercritical expansion conditions, the flow rate ratio of gas passingthrough the orifices is determined by the ratio of cross sectional areasof the orifices.

Now in accordance with FIG. 1, assuming that cross sectional areas oforifices 3, and 4 a to 4 d are S₁, S₂a, S₂b, S₂c, S₂d, respectively, theflow rate of the No. 1 flow diverting pipe passage 1 is Q₁, the flowrate of the No. 2 flow diverting pipe passage 2 is Q₀, and the supplyflow rate in total is Q, so that the flow diverting ratio γ=Q₁/Q₀ can beexpressed by the following equation (1):γ=Q ₁ /Q ₀ =S ₁/(S ₂ a+(S ₂ b+S ₂ c+S ₂ d))  (1)

As stated above, the flow diverting ratio γ is made to be γ=1/1 to1/1.35 (in 8 steps for every 5%), thus it being needed that thefollowing equations (2) and (3) hold, namelyS ₁ /S ₂ a=1/1  (2),S ₂ a/S ₂ b/S ₂ c/S ₂ d=100/20/10/5  (3).

Next, computation of the total sum of the cross sectional areas oforifices S₁, and S₂a to S₂d, and of the individual cross sectional areasS₁, and S₂a to S₂d is explained. Now, when the internal pressure of thechamber 7 is made to be 10 Torr, then pressure P₂₁, P₂₂ of thedownstream side from the orifice is approximately 20 Torr at the maximumwhen taking pressure loss of valves Vb to Vd, and the like, intoconsideration. In order that critical expansion conditions hold, it isrequired that the total cross sectional area S_(T) of all orifices isdetermined so that pressure P₁ on the upstream side from the orificebecomes 40 Torr (i.e., P₁/P₂=more than 2) when valves Vb to Vd are fullyopened.

In accordance with the present invention, the total sum S_(T) of thecross sectional areas of orifices S₁, and S₂b to S₂d is computed usingthe equations for the orifice CV value, as shown in the below-mentionedequations (4) and (5):Cv=α×S _(T)/17  (4),Cv=Qg/(2019×P ₁)×(Gg(273+t))  (5).In equations (4) and (5), a designates a correction coefficient (i.e,0.8), S_(T) designates the total cross sectional area of all orifices(mm²), Qg designates the flow rate (i.e., m³/h=0.06), P₁ designatespressure on the upstream side from an orifice (i.e., MPa abs=0.0053), Ggdesignates the specific gravity of the gaseous fluid (e.g., 0.97), tdesignates fluid temperature (i.e., ° C.=21). In accordance with thepresent embodiment, all computations are performed for the total flowrate Q of the gas is 1 SLM, pressure P₁ on the upstream side from theorifice is 40 Torr, the type of gas used is N₂, and the gas temperatureis 21° C.

In accordance with the aforementioned equations (4) and (5), the totalsum S_(T) of the cross sectional opening areas of orifices S₁, and 52 ato S₂d becomes S_(T)=2.01 mm², and with the aforementioned equations (1)to (3), the cross sectional opening areas of orifices S₁, and S₂a to S₂dbecome S₁=S₂a=0.855 mm², S₂b=0.171 mm², S₂c=0.086 mm², and S₂d=0.043mm², respectively.

Now, as shown in FIG. 1, for example, when open/close valves Vb to Vdare made or operated to be fully opened, then the flow ratio γ becomesγ=Q₁/Q₀=S₁/(S₂a+S₂b+S₂c+S₂d)=1/1.35. When the open/close valves Vb to Vdare made, or operated, to be fully closed, then the flow ratio γ becomesγ=Q₁/Q₀=S₁/S₂a=1/1. Furthermore, when the open/close valve Vb is made tobe opened, and valves Vc and Vd are made to be closed, then the flowratio γ becomes γ=Q₁/Q₀=S₁/(S₁a+S₂b)=1/1.2, and the flow ratio γ=Q₁/Q₀is regulated between 1/1 and 1/1.35 in 8 steps for every 5% by means ofswitching the state of the open/close valves Vb to Vd. In accordancewith the embodiment shown in FIG. 1, the apparatus A is made so that gasflow is supplied to the chamber 7 through two flow diverting pipepassages, namely, the No. 1 flow diverting pipe passage 1 and the No. 2flow diverting pipe passage 2. However, it goes without saying thatthree or more flow diverting pipe passages can be employed, and one or aplurality of pipe passages among them can be equipped with a pluralityof branch pipe passages.

Embodiment 1

It is necessary, in reality, that actually measured values are providedregarding the flow rate characteristics and correction coefficient foran orifice member OF having a small cross sectional area. Therefore,measurements of correction coefficients, and the like, were conducted ontwo types of orifices OF, as shown in FIG. 2 and FIG. 3, by using theflow rate characteristics testing device shown in FIG. 4. Specifically,in accordance with the present embodiment, an orifice OL is formed byperforming 1-step cutting of an orifice member OF having an internaldiameter of 0.3 mm or more, as shown in FIG. 2, and an orifice OL isformed by performing 2-step cutting of OL₁, OL₂ in the orifice member OFhaving an internal diameter of 0.3 mm or less as shown in FIG. 3.Whether to choose 1-step cutting or 2-step cutting is determinedappropriately depending on the thickness of the orifice member, accuracyof the processing machine, and the like.

The orifice member OF is formed as a so-called gasket type. The orificemember OF is changeably and hermetically inserted and fixed into anorifice holder (not illustrated) that is inserted into a pipe passage.In accordance with the present embodiment, orifice members as shown inFIG. 2 are employed as orifice members having diameters of 0.3 mm, 0.4mm and 0.9 mm, and an orifice member as shown in FIG. 3 is employed asan orifice member having a diameter of 0.2 mm.

Flow rate characteristics and correction coefficient of each orificemember OF were actually measured with the testing device as shown inFIG. 4. In particular, as shown in FIG. 4, 8 a, 8 b designate N₂ supplysources, 9 designates a mol block, 10 a,10 b designate pressureregulators, OF designates an orifice member, 11 designates a vacuumgauge (100 Torr

Baratron), 12 designates an open/close control valve, and 13 designatesa vacuum pump. In this case, the measurement accuracy of the mol blockis ±0.2% rdg, the measurement accuracy of the pressure regulators 10 a,10 b is ±0.2% F.S. (1 to 40%) and ±0.5% S.P. (40 to 100%).

Pressure P₁ on the upstream side from the orifice member OF wasregulated using a pressure regulator 10 a, and the gas flow rate passingthrough the orifice was measured with a mol block 9. Pressure on thedownstream side from the orifice member OF was regulated using adownstream side pressure adjustor 10 b, thus the dependence of thedownstream side pressure P₂ was ascertained.

FIG. 5( a) and FIG. 5( b) show flow rate characteristics of orificemembers OF in accordance with the present embodiment. FIG. 5( c) showsthe correction coefficient α computed from the data of FIG. 5( a) andFIG. 5( b).

Using the test results of the aforementioned embodiment 1, orificediameters and correction coefficients of the No. 1 flow diverting pipepassage 1 and branch pipe passages 2 a, 2 b, 2 c, 2 d, shown in FIG. 1,are selected by making pressure P₁ on the upstream side from theorifices 64 Torr.

TABLE 1 Reference characters Pressure P1 on and numerals for flow theupstream side diverting pipe passage from orifices Correction and branchpipe Orifice diameter (Torr) coefficient Flow rate ratio passages inFIG. 1 (mm) 64 0.7 100 1 0.9 0.6 5 2d 0.2 0.7 10 2c 0.3 0.7 20 2b 0.40.7 100 2a 0.9

FIG. 6 shows the relationship between pressure P₂ on the upstream sidefrom an orifice and flow rate measuring accuracy in the case whereinpressure P₂ on the downstream side from the orifice member OF is made tobe 20 Torr. When pressure P₂ on the downstream side from an orificereaches 20 Torr, it is understood, as apparent from FIG. 6, thatpressure P₁ on the upstream side from the orifice must be maintainedmore than 64 Torr in order that the measurement value error (rdg. error)be kept within 1% so as to make the measurement accuracy the same asthat when pressure P₂ on the downstream side from the orifice is made tobe in a state of vacuum.

Table 2 shows the measurement results obtained from the aforementionedembodiment. It is necessary that the total cross sectional opening areabe 1.018 mm² when pressure P₁ on the upstream side from the orifice is64 Torr, the gas supply flow rate Q is 1 SLM, the gas temperature is 21°C., the coefficient of the gas (i.e., the gas specific gravity) is 0.97(N₂), and correction coefficient is 1. When the area ratio of theorifices is made to be the same (i.e.,S₁/S₂a/S₂b/S₂c/S₂d=100/100/20/10/5) as in FIG. 1, the orifices 3, and 4a to 4 d, the flow rate ratio γ, the cross sectional orifice area(correction coefficient 0.6 and 0.7), the computed orifice diameter(mm²) (correction coefficient 0.6 and 0.7), and the selected diameter(mm) of the orifice as measured, are as shown in Table 2.

TABLE 2 Cross Cross Cross section section section Orifice OrificeReference area area area diameter diameter characters (mm²) (mm²) (mm²)(mm) (mm) Selected and Flow (Correction (Correction (Correction(Correction (Correction orifice numerals rate coefficient: coefficient:coefficient: coefficient: coefficient: diameter for orifice ratio 1)0.6) 0.7) 0.6) 0.7) (mm) 3  100 0.433 0.722 0.619 0.959 0.888 0.9 4b 200.087 0.144 0.124 0.429 0.397 0.4 4c 10 0.043 0.072 0.062 0.303 0.2810.3 4d 5 0.022 0.036 0.031 0.214 0.198 0.2 4a 100 0.433 0.722 0.6190.959 0.888 0.9

In the case wherein the orifice diameter has been manufactured inactuality to be 0.5 mm, it is desirable that the correction coefficientof 0.6 is chosen for an orifice diameter of 0.25 mm or less, and thatthe correction coefficient of 0.7 is chosen for an orifice diameter of0.30 mm or more.

In accordance with the aforementioned embodiment, there are employed twoflow diverting pipe passages, namely, the No. 1 flow diverting pipepassage 1 and the No. 2 flow diverting passage 2. However, it goeswithout saying that more than two flow diverting pipe passages can beemployed. In the case wherein a plurality of flow diverting pipepassages are employed, one or more of the flow diverting pipe passagesamong them are made to be ones equipped with the orifice 3, which has agiven opening area S₁, and the remaining flow diverting pipe passagesare made to be ones equipped with branch pipe passages 2 a to 2 d.

Furthermore, in accordance with the aforementioned embodiment, it ispossible that when setting the flow rate ratio as 1/1.35, the flowdiverting ratio may be selected in 8 steps for every 0.5. However, itgoes without saying that the range and switching size of the flowdiverting ratio can be set arbitrarily.

In addition, with the present embodiment, it is basically so made thatan orifice is employed. However, to replace an orifice, a so-calledcritical nozzle or a gap between a valve body and a valve seat of ametal touch type diaphragm valve can be also employed.

In accordance the aforementioned embodiment shown in FIG. 1, there isformed the No. 1 orifice 3, having a given opening area S₁, within theone orifice piece. However, it is possible that the No. 1 orifice 3,having a given opening area S₁, (S₁=S₁₁+S₁₂), is formed by means of anorifice 3 a having a given opening area S₁₁ and an orifice having anadjustable opening area S₁₂ (e.g. a metal touch type diaphragm valve,and the like) that are connected in parallel. Consequently, thisstructure is useful because, by making the opening area S₁₂ of oneorifice out of two component orifices adjustable, the size of theopening area S₁ of the No. 1 orifice 3 is regulated over a certainrange, and then is fixed following adjustment.

FIGS. 11 and 12 are block diagrams of a flow rate ratio variable typefluid supply apparatus in accordance with the present invention. InFIGS. 11 and 12, Q, Q₀, Q₁, and Q_(a) to Q_(d), designate flow rates. 1designates the No. 1 flow diverting pipe passages, 2 a, 2 b, 2 c, and 2d designate branch pipe passages, 3 designates the No. 1 orifices, 4designates the No. 2 orifices, S₁ to S_(n) and S₂a to S₂d designatecross sectional areas of orifices, Va, Vb, Vc, and Vd designateopen/close valves, 6 designates a flow rate control system and 7designates a process chamber.

The present invention can be utilized not only as a flow rate ratiovariable type fluid supply apparatus, with which gases are supplied to achamber used with semiconductor manufacturing facilities, but also as aflow rate ratio variable type fluid supply apparatus for supplying gasesto various gas supply equipment.

What is claimed is:
 1. A flow rate ratio variable type fluid supplyapparatus, comprising: (a) a flow rate control system, wherein the flowrate control system supplies gas of a flow rate Q; (b) a plurality offirst flow diverting pipe passages connected to the flow rate controlsystem so that gas of flow rate Q is diverted to the plurality of firstflow diverting pipe passages, wherein each first flow diverting pipepassage is supplied with a prescribed flow rate of diverted gas so thatgas of flow rate Q is supplied to a chamber through a plurality ofoutlets; (c) at least one first orifice member installed on at least oneof the plurality of first flow diverting pipe passages, wherein eachfirst orifice member comprises a first orifice formed therein having afirst opening area, and any first flow diverting pipe passages that doesnot have a first orifice member installed forms a second flow divertingpipe passage to which a plurality of branch pipe passages are connectedin parallel, wherein the plurality of outlets consists of the outlets ofthe plurality of first flow diverting pipe passages and the outlets ofthe second flow diverting pipe passages so that the gas of flow rate Qis supplied to a plurality of positions in the chamber through theplurality of outlets; (d) a plurality of second orifice membersinstalled on the plurality of branch pipe passages, wherein each secondorifice member comprises a second orifice formed therein having a secondopening area; and (e) a plurality of open/close valves installed on all,or some of the plurality of branch pipe passages so that gas of flowrate Q is diverted and flows to the plurality of first flow divertingpipe passages with a flow rate ratio for each first flow diverting pipepassage that is equivalent to the ratio of the respective first openingarea of the corresponding first orifice member on the correspondingfirst flow diverting pipe passage and a total opening area of allflow-passable second orifices, wherein the total opening area is the sumof the second opening areas of those second orifice members that areflow-passable, and wherein the flow rate ratio is regulated by anopen/close operation of the open/close valves installed on the branchpipe passages.
 2. A flow rate ratio variable type fluid supply apparatusaccording to claim 1, wherein the first orifice formed in the firstorifice member comprises a first orifice portion that has a constantopening area connected in parallel with a second orifice portion thathas an adjustable opening area.
 3. A flow rate ratio variable type fluidsupply apparatus according to claim 1, wherein the first orifice and thesecond orifice are 2-step cutting type orifices having two differentorifice portions of different diameter, wherein each 2-step cutting typeorifice is arranged so that gas flows from a first step orifice portionof the 2-step cutting type orifice to a second step orifice portion ofthe 2-step cutting type orifice, and wherein the second step orificeportion has a larger diameter than the first step orifice portion.
 4. Aflow rate ratio variable type fluid supply apparatus, comprising: (a) aflow rate control system, wherein the flow rate control system suppliesgas of a flow rate Q; (b) a plurality of first flow diverting pipepassages connected to the flow rate control system so that gas of flowrate Q is diverted to flow to the plurality of first flow diverting pipepassages, wherein each first flow diverting pipe passage is suppliedwith a prescribed flow rate of diverted gas so that gas of flow rate Qis supplied to a chamber through a plurality of outlets; (c) a pluralityof first orifice members installed on all but one of the plurality offirst flow diverting pipe passages, wherein each first orifice membercomprises a first orifice having a corresponding first opening area, andthe one first flow diverting pipe passage without a first orifice memberforms a second flow diverting pipe passage to which a plurality ofbranch pipe passages are connected in parallel, wherein the plurality ofoutlets consists of the outlets of the plurality of first flow divertingpipe passages and the outlet of the second flow diverting pipe passageso that the gas of flow rate Q is supplied to a plurality of positionsin the chamber through the plurality of outlets; (d) a plurality ofsecond orifice members installed on the plurality of branch pipepassages so that there is a second orifice member installed on each ofthe plurality of branch pipe passages, and each second orifice membercomprises a second orifice having a corresponding second opening area;and (e) a plurality of open/close valves installed on all, or some of,the plurality of branch pipe passages so that gas of flow rate Q isdiverted to flow to the plurality of first flow diverting pipe passageswith a flow rate ratio equivalent to the ratio of the respective firstopening area of the corresponding first orifice member on thecorresponding first flow diverting pipe passage and a total opening areaof a flow-passable orifices on the one second flow diverting pipepassage, wherein the total opening area of the flow-passable orifices onthe second flow diverting pipe passage is regulated by open/closeoperation of the plurality of open/close valves installed on theplurality of branch pipe passages.
 5. A flow rate ratio variable typefluid supply apparatus according to claim 4, wherein the first orificeformed in the first orifice member comprises a first orifice portionthat has a constant opening area connected in parallel with a secondorifice portion that has an adjustable opening area.
 6. A flow rateratio variable type fluid supply apparatus according to claim 4, whereinthe first orifice and the second orifice are 2-step cutting typeorifices having two different orifice portions of different diameter,wherein each 2-step cutting type orifice is arranged so that gas flowsfrom a first step orifice portion of the 2-step cutting type orifice toa second step orifice portion of the 2-step cutting type orifice, andwherein the second step orifice portion has a larger diameter than thefirst step orifice portion.
 7. A flow rate ratio variable type fluidsupply apparatus, comprising: (a) a chamber, wherein the chamber is asemiconductor manufacturing chamber, and wherein the chamber has two gassupply locations; (b) a flow rate control system, wherein the flow ratecontrol system supplies gas of a flow rate Q to the chamber, and whereinthe two gas supply locations are a first supply location and a secondsupply location; (c) a first flow diverting pipe passage and a secondflow diverting pipe passage connected to the flow rate control system sothat gas of flow rate Q is diverted to flow to the first flow divertingpipe passage so that gas of flow rate Q₁ flows through the first flowdiverting pipe passage and gas of flow rate Q₀ flows through the secondflow diverting pipe passage, wherein Q=Q₁+Q₀, so that gas of flow rate Qis supplied by the combined flow of gas through an outlet of the firstflow diverting pipe passage and an outlet of the second flow divertingpipe passage, respectively, to the first supply location and the secondsupply location in the chamber at the gas flow rate Q; (d) a firstorifice member installed on the first flow diverting pipe passage,wherein the first orifice member comprises a first orifice having acorresponding first opening area; (e) a plurality of branch pipepassages connected in parallel to the second flow diverting pipepassage; (f) a plurality of second orifice members installed on theplurality of branch pipe passages so that each branch pipe passage has asecond orifice member installed thereon, wherein each second orificemember comprises a second orifice having a corresponding second openingarea; and (g) a plurality of open/close valves installed on all, or someof the branch pipe passages so that gas of flow rate Q is diverted toflow to the first flow diverting pipe passage at the flow rate Q₁ and tothe second flow diverting pipe passage at the flow rate Q₀ with a flowrate ratio Q₁/Q₀ equivalent to the ratio of the first opening area ofthe first orifice installed on the first flow diverting pipe passage anda total opening area of flow-passable orifices of the second flowdiverting pipe passage, wherein the flow rate ratio Q₁/Q₀ is regulatedby controlling the total opening area of the flow-passable orifices ofthe second flow diverting pipe passage by open/close operation of theopen/close valves installed on the branch pipe passages.
 8. A flow rateratio variable type fluid supply apparatus according to claim 7, whereinthe first orifice formed in the first orifice member comprises a firstorifice portion that has a constant opening area connected in parallelwith a second orifice portion that has an adjustable opening area.
 9. Aflow rate ratio variable type fluid supply apparatus according to claim7, wherein the plurality of branch pipe passages includes a first branchpipe passage comprising a third orifice formed therein, wherein thethird orifice has a third opening area and the first opening area of thefirst orifice member of the first flow diverting pipe passage is made tobe identical to the third opening area, and the first branch pipepassage is connected to the second flow diverting pipe passage withoutan open/close valve being installed on the first branch pipe passage.10. A flow rate ratio variable type fluid supply apparatus according toclaim 7, wherein four branch pipe passages are connected in parallel tothe second flow diverting pipe passage, wherein the four branch pipepassages include a first branch pipe passage comprising a third orificeformed therein that has a third opening area, a second branch pipepassage comprising a fourth orifice formed therein that has a forthopening area, a third branch pipe passage comprising a fifth orificeformed therein that has a fifth opening area, and a fourth branch pipepassage comprising a sixth orifice formed therein that has a sixthopening area, wherein the third opening area of the third orifice of thefirst branch pipe passage and the first opening area of the firstorifice member of the first flow diverting pipe passage are identical,and the fourth opening area, the fifth opening area, and the sixthopening area of the fourth orifice, the fifth orifice, and the sixthorifice, respectively, of the second branch pipe passage, the thirdbranch passage, and the fourth branch passage, respectively, are made tobe 5%, 10% and 20%, respectively, of the first opening area of the firstorifice of the first flow diverting pipe passage, and each of the secondbranch pipe passage, the third branch pipe passage, and the fourthbranch pipe passage has an open/close valve installed thereon.
 11. Aflow rate ratio variable type fluid supply apparatus according to claim7, wherein the open/close valves are valves having an open/closeoperation so that the branch pipe passages having an open/close valveinstalled thereon can be only either fully opened or fully closed.
 12. Aflow rate ratio variable type fluid supply apparatus according to claim7, wherein the first opening area of the first orifice, and the secondopening area of each second orifice, is set at an appropriate value byselection of a correction coefficient depending on orifice shape andpressure conditions upstream from each orifice, respectively.
 13. A flowrate ratio variable type fluid supply apparatus according to claim 12,wherein the correction coefficient is selected to be 0.6 or 0.7depending on how the shape of a diameter φ of the first orifice and thesecond orifices are processed.
 14. A flow rate ratio variable type fluidsupply apparatus according to claim 7, wherein a gap between a diaphragmbody and a valve seat of a metal diaphragm serves as the first orificeand as the second orifices.
 15. A flow rate ratio variable type fluidsupply apparatus according to claim 7, wherein the first orifice and thesecond orifice are 2-step cutting type orifices having two differentorifice portions of different diameter, wherein each 2-step cutting typeorifice is arranged so that gas flows from a first step orifice portionof the 2-step cutting type orifice to a second step orifice portion ofthe 2-step cutting type orifice, and wherein the second step orificeportion has a larger diameter than the first step orifice portion.